Freeze-thaw resistance is a key durability factor for concrete pavements. Recommendations for the air void system parameters are normally 6% ± 1% total air and spacing factor ? 0.20 mm (0.008 in.). However, it was observed that some concretes that did not possess these commonly accepted thresholds presented good freeze-thaw resistance in laboratory studies. A study evaluated the freeze-thaw resistance of several marginal air void mixes, with two different types of air-entraining admixtures: a Vinsol resin admixture and a synthetic admixture. The study used rapid cycles of freezing and thawing in plain water, in the absence of deicing salts. For specific materials and concrete mixture proportions used in this project, the marginal air mixes (concretes with fresh air contents of 3.5% or higher) presented an adequate freeze-thaw performance when Vinsol resin-based air-entraining admixture was used. The synthetic admixture used in the study did not show the same good performance as the Vinsol resin admixture did.